While selecting plants to bring to your garden, considerations begin with basic cultural issues: exposure (sun, partial shade, full shade); moisture (infrequent; regular; ample); and drainage (fast, normal, boggy). Other more advanced cultural issues exist for future discussions.
Once we satisfy the basic cultural conditions, the selection process can proceed to aesthetic issues. There are many such issues, potentially, because they involve site-specific priorities and gardener-specific preferences. Today’s column addresses the mature sizes of plants as factors to consider when selecting a new plant for the landscape.
Plant size might seem an obvious concern, but an all-too-common error is to install a plant where it will grow eventually to intrude on a pathway, overwhelm nearby plants, unintentionally block a view, or reach over a fence into a neighbor’s space.
Such issues could arise with all kinds of plants, although some grow more slowly than others and could become a problem only after several years of maturation.
Thoughtful gardeners favor purchases of small plants, knowing that they could buy at lower cost by growing the plant themselves rather paying a nursery to care for the plant for one or more seasons. That’s a good and frugal practice for gardeners, and it brings the additional pleasure of watching the plant grow in the garden.
Garden centers often carry selections of herbaceous perennials and succulents in four-inch—and even two–inch—containers, and woody shrubs and trees in one-gallon or smaller containers. These small plants often have labels that indicate their mature size, and the gardener has the responsibility to read the label and select plants that are suitable for the space they are intended to fill.
Small plants can be misleading, however, when the label provides insufficient information about its eventual size, or when the buyer overlooks this important information. If the label doesn’t tell the story, search for the plant’s botanical name on the Internet to learn about its full size.
For example, I recently brought home a four-inch pot holding a Dasylirion longissima. The common name, Mexican Grass Tree, suggests its eventual size, which is eight-to-ten feet wide, with a flower stalk that could reach up to fifteen feet. I’m looking for the right spot to plant it.
My garden already has a Dasylirion wheeleri, a related plant that is known as Desert Spoon. This plant has already grown to its full size of three feet wide, and once developed an impressive flower spike over eight feet high. It is, however, too close to a walkway, and its leaves have saw-tooth edges that are inhospitable to passersby and the occasional weeder. I will need to bundle it before attempting to dig up and move it to a better spot.
Large plants can be excellent specimens in the garden so this “mature size alert” is not intended to discourage the use of botanical behemoths. Given enough space, big plants can be striking additions to the garden, but it’s best when the gardener knows their mature sizes before planting.